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Ren Ziwei of China won the men's 1,000m short-track speed skating final at the Beijing 2022 Winter Olympic Games at the Capital Gymnasium

February 12, 2022

Ren Ziwei of China won the men's 1,000m short-track speed skating final at the Beijing 2022 Winter Olympic Games at the Capital Gymnasium

 

China's Ren Ziwei won the gold medal and Li Wenlong the silver medal in the men's 1,000m short-track speed skating final at the Beijing Winter Olympics.  

 

In this winter, while we celebrate China, is it true that we also have the desire to skate in our hearts. I checked the background knowledge of skating, happened to see the content related to heat treatment, I want to share with you quickly.  

 As for this skater, it is not a real knife, but a steel blade mounted under the sole of the skate, which is the most important part of the skate.  

Figure skate blade belongs to thin wall parts (thickness 3.6-4.0mm).  Heat treatment is difficult.  Previously, carburizing and quenching was performed in a salt bath furnace with plug-in electrodes, at 90°C X2-2.5h.  Due to the poor uniformity of furnace temperature and molten salt, the surface hardness of carburized and hardened workpiece is not uniform, ranging from 43HRC to 61.5HRC, the deformation of lateral bending, vertical bending and distortion are very large when heat treatment, straightening is difficult, some can not be straightened, had to scrap (such as distortion deformation).  In straightening and grinding, there are often problems such as broken edge and grinding crack.  Due to high hardness, high stress and serious electroplating hydrogen embrittlement, it is difficult to guarantee the quality of products, and the pass rate of one time delivery is only 52%.  Because of frequent deoxidation, cooling dregs, product quality is difficult to control.  
 
The push and pull material sealed box carburizing and quenching linkage line is selected. Acetone is used as enriched gas and methanol is used as carrier for carburizing and quenching the pattern ice cutter.  The production line is composed of drip controlled atmosphere box type multi-purpose furnace, quenching oil tank (back chamber carburizing, front chamber quenching), multi-function cleaning machine (spray, rinsing, drying), hot air tempering furnace, driving and so on.  
 
In the process of furnishing and controlling the atmosphere in the furnace, two sets of drip pipelines are used with the flow rate of 10-200mL /min.  One of them is standby, solenoid valve automatically control flow, oxygen probe monitoring and through the drawing instrument to record carbon potential, furnace temperature, time and so on.  At the same time, steel foil is used to fix carbon, and the oxygen probe is often modified to monitor the corresponding value reflected on the drawing instrument.  In normal operation, the fan stirs the atmosphere at a speed of 450-600r /min to ensure the atmosphere uniformity during production.  The mature process is 9℃x 140min carburizing after direct quenching, oil temperature 70℃, quenching stirrers at a high speed of 1 000r/min stirring, at the same time quenching plate heat exchanger for rapid heat exchange, so as to ensure the uniformity of hardness and the required micro deformation of the thin-wall workpiece.